Large differences in cardiovascular disease (CVD) outcomes have been observed across ethnic and gender groups which are not fully explained by consideration of traditional and novel CVD risk factors. For example, African Americans have a considerably higher prevalence of hypertension, left ventricular dysfunction, and heart failure than Caucasians despite lipid patterns and coronary artery calcium levels that generally show relatively favorable distributions. However, only limited research has addressed the role of sleep disorders in influencing CVD in ethnic minorities despite evidence that sleep disorders disproportionately affect minority populations and, through pro-inflammatory or autonomic nervous system dysregulation, operate as risk factors for hypertension and CVD. In this proposed ancillary study to the Multi-Ethnic Study of Atherosclerosis (MESA), we aim to perform standardized in-home polysomnography and 7-day wrist actigraphy in 2500 African American, Hispanic, Asian American and Caucasian individuals participating in MESA Exam 5 to derive indices of sleep apnea, quality, duration and timing. Newly collected sleep data will be rigorously standardized and comprehensively analyzed by a central Reading Center. By capitalizing on the rich clinical, physiological, anthropomorphic, and biochemical data collected longitudinally by MESA over 10 years, we will test the associations between indices of sleep apnea (apnea hypopnea index, nocturnal hypoxemia), sleep duration and quality, slow wave activity, and circadian placement with the indices of CVD risk, subclinical CVD and clinical CVD as outcomes. Finally, we will quantify the extent to which sleep disorders and patterns account for previously observed variations in CVD among ethnic and sex groups. By defining the role of sleep disorders in CVD in ethnic minorities, these activities may direct future interventions directed at reducing ethnic disparities in chronic health conditions.